Major news in space this week. We now have a 10th planet, and a lake of water ice has been found in a crater on Mars. Just look to the left! Incredible sight, isn't it? Water does exist on Mars, and that means it's very likely that we might find evidence of old life, or possibly even life living deeper in the soil. (story)
And yes, we do have a 10th planet too! 2003UB313 is it's current name, although a more pronouncable name is being considered. I'll update this when it is named. The body is at least the size of Pluto, though it has a very eccentric orbit at a high angle to the orbital plane of our solar system. It, along with Pluto, are thought to be objects from the Kuiper Belt, which is a sphere of icy, rocky objects at the outer edge of our solar system. Of course, this also calls into question whether objects the size of Pluto and this new object should actually be considered planets. But either way, it's pretty cool, and sobering, to know that there are still things in our own solar system we don't know about yet.
Update: As a point of interest, a few days before, there was an object 70% the size of Pluto found. Many months ago an object 50% the size of Pluto was also found, named Sedna by its discoverers. Wrote Shakespeare: "There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy."
Update 2: I've been recuse in forgetting to mention that there is much consternation about the status of Pluto and objects similar in size to Pluto, and whethe they should be considered actual 'plantets'. I must say I'm on the side of considering objects like Pluto to not be planets. However, if we are going to consider Pluto a planet simply because it's always been considered as such, then it must be argued that objects bigger than Pluto must be considered planets as well. However, it's also predicted be some that Mars-size objects are lurking out there as well. Now, I'm not sure how easy it is for bodies bigger than Mercury to be knocked into orbits outside of the orbital plane, but I think I good operational definition is to say that planets are bodies large enough to become spherical due to gravity and whose orbits focus around a star and lie in the same plane. Of course, I could be wrong, but given our model of planet formation, it is likely that most planets will originate in the same plane.